<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>DOMParser 类型</title>
</head>
<body>
  <script>
    const parser = new DOMParser();
    const xmldom = parser.parseFromString('<root><child /></root>', 'text/xml');

    console.log(xmldom.documentElement.tagName);  // "root"
    console.log(xmldom.documentElement.firstChild.tagName);  // "child"

    const anotherChild = xmldom.createElement('child');
    xmldom.documentElement.appendChild(anotherChild);

    const children = xmldom.getElementsByTagName('child');
    console.log(children.length);  // 2
  </script>
</body>
</html>